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Vector Control And Dynamics Of Ac Drives

Assessment of the energy efficiency estimation methods on induction motors considering real-time monitoring

A wet packed bed scrubber combined with dry oxidation by indirect DBD plasma for conversion of NO to NO 2 and wet reduction with two reduction agents of Na 2 S and Na 2 SO 3 to remove NO 2 was developed at room temperature for semiconductor manufacturing industries. The design and operation parameter for the wet scrubber such as gas concentration, liquid to gas ratio, reducing agent concentration, residence time and pressure drop were investigated at 2 m3/min and 200 ppm of pure NO gas. Na 2 S solution was more suitable than Na 2 SO 3 with less chemical consumption and liquid to gas ratio. Removal efficiency over 80% was achieved with liquid to gas ratio of 10 L/m3, reduction agent solution of 0.1% w/w which corresponds to ORP of −310 mV and pH of 12.3, residence time of 2 sec, and pressure drop of 25 mmAq/m, respectively. Finally, a demonstration test of the wet scrubber was conducted for 1 month with exhaust gas from perfluorinated compounds (PFCs) gas scrubber at the rooftop of a semiconductor manufacturing plant in Korea. In order to suppress H 2 S as byproducts of the wet scrubber, pH over 12 was carefully controlled with NaOH solution because commonly highly acid gases such as HF and HCl were fed from the manufacturing process. The NOx removal efficiency was average 83.8% which was very similar to those obtained from the lab tests. These results indicate that the combination of the dry oxidation and wet reduction method could be a promising solution to remove NOx from semiconductor manufacturing industries.

NOx removal performance of a wet reduction scrubber combined with oxidation by an indirect DBD plasma for semiconductor manufacturing industries

As UPSs Uninterruptible Power Supplies ou Fontes de Energia Ininterrupta sao equipamentos empregados para prover o fornecimento de energia continuo e de alta qualidade a cargas criticas, elevando a disponibilidade e a confiabilidade do fornecimento a niveis muito superiores aos originalmente encontrados nas redes das concessionarias. Entretanto, como todo equipamento eletronico, a propria UPS esta tambem sujeita a falhas. Niveis mais elevados de confiabilidade podem ser alcancados por meio do uso de redundância, a qual pode ser realizada pela conexao em paralelo das UPSs. O presente trabalho concentra-se no estudo do paralelismo de UPSs como forma de elevar a confiabilidade ou a capacidade de potencia do fornecimento de energia, sem a utilizacao de comunicacao entre as unidades, o que requer o uso apenas das informacoes mensuraveis localmente. Cada um dos subsistemas necessarios a implementacao do paralelismo sem comunicacao e investigado em detalhes. Sao modelados, analisados e comparados os metodos de calculo de potencia ativa e reativa e as tecnicas de sincronismo (PLLs) no sistema monofasico. As origens dos erros de divisao de potencia ativa e reativa em regime permanente e suas formas de mitigacao sao tambem investigadas. O estudo do controle da tensao de saida da UPS e desenvolvido em tempo discreto considerando o atraso de calculo do processador e a estrategia de PWM. O projeto do controlador discreto e proposto visando a conformidade com as normas e ao mesmo tempo a estabilidade do paralelismo. A partir da analise do paralelismo de uma UPS com a rede eletrica sao propostas tecnicas de desacoplamento multivariavel com fins de ampliacao da faixa de estabilidade de pequenos sinais em funcao do valor e da natureza da impedância de conexao entre as UPSs. As tecnicas propostas sao validadas atraves de resultados experimentais.

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Contribuição ao controle digital doparalelismo sem comunicação desistemas de energia ininterrupta

Monitoring energy consumption and condition of electric motors is important for economical purposes and safe operation of drives and processes in the industry. These activities are especially valid in processes requiring high availability such as those found in mining and metals industry. Methods able to implement these functions without process interruption and/or requiring minimum changes on the drive configuration are extremely welcome. The air-gap torque estimator is at the core of the main efficiency-estimation methods used today; therefore, it is crucial to its successful implementation. Most of the torque estimation algorithms require two or three voltage and current measurement to be implemented. Unfortunately, this number of sensors is not always available for all the motors used in industrial processes. Aiming to face this problem, a solution requiring data acquisition of the current and voltage of only one phase suited to be used in algorithms of efficiency estimation of in-service induction motors was presented in a previous paper. The installation in the motor control center cabinet of a pair of sensors to measure these variables is more feasible and, sometimes, it is done for monitoring and protection purposes. In this paper, the method governing equations are simplified further and the performance under unbalanced voltage condition investigated and improved. Simulation and experimental results are used to check the validity and performance of the proposed technique.

A Simple Torque Estimator for In-Service Efficiency Determination of Induction Motors

Monitoring energy consumption and condition of electric motors is important for economical purposes and safe operation of drives and processes in industry. Those activities are especially valid in processes requiring high availability such as those founded in mining and metals industry. Methods able to implement these functions without process interruption and/or requiring minimum changes on the drive configuration are extremely welcome. The air-gap torque estimator is at the core of the main efficiency estimation methods used today and therefore it is crucial to its successful implementation. Most of the torque estimation algorithms require two or three voltage and current measurement to be implemented. Unfortunately, this number of sensors is not always available for all the motors used in industrial processes. Therefore, a solution employing a reduced number of sensors is necessary. In order to meet this requirement, this paper presents a new and simple technique to estimate torque that is able to be used in algorithms of efficiency estimation of in-service induction motors. The technique requires data acquisition of current and voltage of only one phase for its implementation. Sensors for measuring these variables are usually available in the Motor Control Center — MCC — cabinet for monitoring and protection purposes. From one phase current and voltage samples, instantaneous values of torque, angular velocity, power and efficiency are calculated. Simulation and experimental results are used to check the validity and performance of the proposed technique.

A simple torque estimator for in-service efficiency determination of induction motors

This paper deals with a small-signal model for analyzing the parallel operation of frequency inverters used in Uninterruptible Power Supplies – UPSs. The UPSs operate without communication with each other and is controlled by the traditional droop method. Initially, small-signal models of a single unit connected to an infinite bus and those referring to several ones connected in parallel are revisited. Then, considering a set of common parameters, comparisons are made between the eigenvalues and the dynamic responses found for two systems: (i) an inverter connected to an infinite bus and (ii) two inverters operating themselves in parallel. Simulations and experimental results have shown the possibility of simplifying the small-signal model to represent the parallelism of frequency inverters operating in several situations, making their analysis and design simpler.

Marcos A. Saldanha

Papers

A simple torque estimator for in-service efficiency determination of induction motors

A Simple Torque Estimator for In-Service Efficiency Determination of Induction Motors

A simplified Small-Signal Model for Analyzing the Parallel Operation of Frequency Inverters in UPS